diff options
author | Oleg Nesterov <oleg@redhat.com> | 2013-07-09 03:01:05 +0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-09 21:33:26 +0400 |
commit | fab840fc2d542fabcab903db8e03589a6702ba5f (patch) | |
tree | 26bd3ecf468ca83fa77e4b02d8c28371a995405d /kernel/ptrace.c | |
parent | 61e305c716c0737c97bd133313cc90e99a93712e (diff) |
ptrace: PTRACE_DETACH should do flush_ptrace_hw_breakpoint(child)
Change ptrace_detach() to call flush_ptrace_hw_breakpoint(child). This
frees the slots for non-ptrace PERF_TYPE_BREAKPOINT users, and this
ensures that the tracee won't be killed by SIGTRAP triggered by the
active breakpoints.
Test-case:
unsigned long encode_dr7(int drnum, int enable, unsigned int type, unsigned int len)
{
unsigned long dr7;
dr7 = ((len | type) & 0xf)
<< (DR_CONTROL_SHIFT + drnum * DR_CONTROL_SIZE);
if (enable)
dr7 |= (DR_GLOBAL_ENABLE << (drnum * DR_ENABLE_SIZE));
return dr7;
}
int write_dr(int pid, int dr, unsigned long val)
{
return ptrace(PTRACE_POKEUSER, pid,
offsetof (struct user, u_debugreg[dr]),
val);
}
void func(void)
{
}
int main(void)
{
int pid, stat;
unsigned long dr7;
pid = fork();
if (!pid) {
assert(ptrace(PTRACE_TRACEME, 0,0,0) == 0);
kill(getpid(), SIGHUP);
func();
return 0x13;
}
assert(pid == waitpid(-1, &stat, 0));
assert(WSTOPSIG(stat) == SIGHUP);
assert(write_dr(pid, 0, (long)func) == 0);
dr7 = encode_dr7(0, 1, DR_RW_EXECUTE, DR_LEN_1);
assert(write_dr(pid, 7, dr7) == 0);
assert(ptrace(PTRACE_DETACH, pid, 0,0) == 0);
assert(pid == waitpid(-1, &stat, 0));
assert(stat == 0x1300);
return 0;
}
Before this patch the child is killed after PTRACE_DETACH.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/ptrace.c')
-rw-r--r-- | kernel/ptrace.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index a146ee327f6a..4041f5747e73 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -469,6 +469,7 @@ static int ptrace_detach(struct task_struct *child, unsigned int data) /* Architecture-specific hardware disable .. */ ptrace_disable(child); clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); + flush_ptrace_hw_breakpoint(child); write_lock_irq(&tasklist_lock); /* |